Although the knowledge and practices of individual clinicians are important for high quality care, it is increasingly the case that health care professionals practice within groups or systems of care. The functioning of those systems in preventing errors, coordinating care among settings and practitioners, and ensuring that relevant, accurate information is available when needed are critical systemic elements of providing high quality care. The proposed study will assess the relationship between hospital quality improvement structures and practices and selected quality indicators in a sample of 854+ hospitals. Two specific study objectives are advanced: (1) to assess the association between hospital quality improvement infrastructure and quality indicators at the hospital level; and (2) to identify the organizational and market conditions under which specific quality improvement practices affect quality indicators at the hospital level. The study will combine unique survey data on hospital quality improvement structures and practices with data derived from hospital discharge abstract data under the HCUP program at AHRQ. Using multivariate statistical analyses, we will examine the main effects of the scope, duration and intensity of hospital QI implementation on hospital-level clinical quality indicators. The study will also examine how leadership for quality, organizational infrastructure and resources for quality, and other organizational and market characteristics moderate the relationship between hospital QI practices and hospital-level clinical quality indicators. Study results will provide policy makers, accrediting bodies, and consumers with more precise information regarding which dimensions of hospital QI exhibit the strongest association with select hospital quality indicators. Study findings may therefore provide the basis for quality improvement standards and benchmarks that emphasize not only widely available quality indicators but also those indicators that are potentially amenable to QI interventions by hospital managers and clinicians. Second, To the extent that our study findings identify the conditions under which particular approaches to hospital quality improvement are associated with more positive quality indicators, hospitals may be able to target those strategies that are particularly suited to their operating environment.